From ef4459a6da0955b533ebfc97a7d756ac090f50c9 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Sat, 5 Dec 2020 21:50:18 +0100 Subject: um: allocate a guard page to helper threads We've been running into stack overflows in helper threads corrupting memory (e.g. because somebody put printf() or os_info() there), so to avoid those causing hard-to-debug issues later on, allocate a guard page for helper thread stacks and mark it read-only. Unfortunately, the crash dump at that point is useless as the stack tracer will try to backtrace the *kernel* thread, not the helper thread, but at least we don't survive to a random issue caused by corruption. Signed-off-by: Johannes Berg Signed-off-by: Richard Weinberger --- arch/um/os-Linux/helper.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/um/os-Linux') diff --git a/arch/um/os-Linux/helper.c b/arch/um/os-Linux/helper.c index 9fa6e4187d4f..feb48d796e00 100644 --- a/arch/um/os-Linux/helper.c +++ b/arch/um/os-Linux/helper.c @@ -45,7 +45,7 @@ int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv) unsigned long stack, sp; int pid, fds[2], ret, n; - stack = alloc_stack(0, __cant_sleep()); + stack = alloc_stack(__cant_sleep()); if (stack == 0) return -ENOMEM; @@ -116,7 +116,7 @@ int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags, unsigned long stack, sp; int pid, status, err; - stack = alloc_stack(0, __cant_sleep()); + stack = alloc_stack(__cant_sleep()); if (stack == 0) return -ENOMEM; -- cgit